Sprue Plate Hole

[alamogunr]

I finally got around to trying a LBT .475, 385 gr. mold yesterday. I couldn't get well filled out boolets. I suspect the reason is that the sprue plate hole is too small. The holes in the LBT sprue plate are the smallest I have seen. If I maintained a steady stream from the pot, alloy would just pile up on top until it could seep into the cavities. Got good bases but the drive bands were rounded.

Has anyone else had this problem? If so, what did you do to correct.

John
W.TN

[dragonrider]

Sounds like you need to enlarge the holes. NOT WITH A DRILL, you need to use a 90 degree countersink. Remove the sprue plate from the mold and place in a milling machine or a drill press vise. With a slow RPM and plenty of oil make your holes larger but no more than 160". I measured several of mine and that is about average. This process will leave a burr on the other side that must be removed, a fine file and then a smooth stone.

[damron g]

use Verals instructions that came with the mold and you will get good bullets.Tip the mold slightly toward the pot and let the metal run from a dipper into the cavities with no contact running back into the pot.With BP you don't get the sprue plate heated up as much as you do by letting it run off as above and that MAY be your problem.You also need to get it hot hot hot.Dip the mold corner in the pot a few seconds and get it heated up well before casting.If you bought it used see if you can get an instruction set from LBT.You need to use his beeswax/graphite lube sticks on the wear points to help galling.

George

[e15cap]

Make sure the sprue plate isnt too tight. Has to have a little wiggle to vent correctly, its kinda of a feel thing. Too tight and you have to push it back, too loose and it swings like a old garden gate. Best, Roger

[alamogunr]

I've got the instructions somewhere. I don't throw anything away. I guess I will have to fire up the plumbers pot and try over filling and draining back into the pot. Also the plumbers pot can get hotter than the bottom pour. I don't like to dip from the bottom pour because of the restricted access. I use a hot plate with an aluminum plate on top to pre-heat my molds. I guess that didn't conduct enough heat to the sprue plate.

John
W.TN

[lwknight]

I would have tried pressure casting first , then worry aboutt he sru plate hole later.

[geargnasher]

....or pressure cast with a rowel ladle like Lyman makes, that means turn the mould 90*, stick the spout in the sprue hole like you want it to be air tight, and slowly rotate them together to fill the mould. Count to two or three after the cavity is full, then pull the ladle away slightly but quickly to "dab" a sprue puddle into the well. If the stream freezes or the ladle spout sticks to the sprue plate, the sprue plate is too cold.

Gear

[alamogunr]

You all have given me several things to try. I have already used the plumber's pot to try over filling and letting the alloy run back into the pot. This worked to get the sprue plate hot and I got some good looking boolets. One big problem. The alignment pins are keeping the mold halves from closing completely. I'm not getting severe fins but they are there and the diameter is about .006 to .008 oversize. Should be around .477-.478. If I use my gloved fingers to push the halves together, it is difficult to open the mold. Just for the heck of it I tried to push one through my Lee .476 sizer. NO WAY! Had to drive it back out with a machine punch.

I've got to do some thinking about those alignment pins. I'm hesitating to get a file that close to the faces of the mold. Any suggestions will be appreciated. I've tried Bull Plate lube. Helped a little but not enough.

John
W.TN

[Edubya]

I'm not familiar with the LBT moulds but most have alignment pins that can be seated deeper. Before you attempt to file it check it over real closely and if it's perfectly clean then maybe you can put a light hammer tap on the pin.

EW

[Echo]

I would most strongly suggest you NOT put a file anywhere near the faces of the mold. If it IS the alignment pins holding the mold open, I believe they can be poked down in a little more to solve the problem.

[crabo]

Sounds like you need to enlarge the holes. NOT WITH A DRILL, you need to use a 90 degree countersink. Remove the sprue plate from the mold and place in a milling machine or a drill press vise. With a slow RPM and plenty of oil make your holes larger but no more than 160". I measured several of mine and that is about average. This process will leave a burr on the other side that must be removed, a fine file and then a smooth stone.

This is the way I do it, except I clean up the sprueplate on the belt sander.

[alamogunr]

I wish I could post a picture of the LBT sprue plate. It is a stamped part with the back side ground(or sanded) smooth. The holes are punched, not milled(or drilled). I don't think that a c'sink would work.

I'm going to try to tap the pins a little deeper and see if that solves the problem. If it does, ladle casting and letting the excess flow back into the pot is not a bad method. Really pretty neat. As I said before, I got good looking boolets, just too big.

From time to time I see posts here that someone wants to size a boolet down .006-.008. I couldn't do it with a Lee push thru sizer. I was using it in my RCBS Rockchucker. I really leaned on it and I'm 6'2", 200#. Might work on a smaller diameter boolet but not on a .475"+ diameter.
Edit: Yes the boolet was lubricated.

John
W.TN

[crabo]

The LBT could easily just be opened up with a drill bit of a larger size. You would still want to deburr it. I just looked at mine.

[Horace]

I bought two LBT moulds of similar weight and diameter both have different sprue hole diameters.The larger of the two cast much better boolits, haven`t talked to Veral about it yet.

Horace

[damron g]

"The alignment pins are keeping the mold halves from closing completely. I'm not getting severe fins but they are there and the diameter is about .006 to .008 oversize."

I have never had to adjust the pins or screws on any LBT i have owned even after many 1000's of bullets.Make sure you are using his mold lube on the alignment pin area or they may not close properly.Don't start messing with an LBT as it is generally an issue of learning to use it properly rather than it needing tweaking.
I have tried ladle contact and BP pressure casting with LBT 22s and 30's and the best luck by far has been with his recommended dipper method.

George

[odoh]

IIRC there wass instructions re seating the alignment guides/pin included w/the mould?